Field of the Invention
The present invention relates vehicle “backup” camera systems and to remotely controlled systems for cleaning soiled objective lenses on video cameras or sensors when mounted in a configuration that is exposed to dirty environments, and more particularly to a fluidic spray apparatus configured to controllably direct a spray onto the lenses of at least two sensors such as video cameras when mounted in a location that is exposed to environments that can cause accumulation of dirt or other debris that impairs their usefulness by a vehicle user.
Discussion of the Prior Art
The US National Highway Traffic Safety Administration (“NHTSA”) has mandated that by 2018 new vehicles must include a rearview or “backup” camera system to minimize the likelihood of “backovers”. A backover is a specifically-defined type of accident, in which a non-occupant of a vehicle (i.e., a pedestrian or cyclist) is struck by a vehicle moving in reverse. Automotive original equipment manufacturers (“OEMs”) are thus adding external rearview cameras to all new cars. In addition, OEMs want more cameras to see into any other blind spot around a vehicle's periphery (behind, to the side, or in front) and all of these cameras necessarily include exterior lens surfaces which will eventually become soiled with road grime, mud and the like. Drivers of large vehicles such as SUVs, Vans, and trucks often find it difficult to move their vehicles from parked positions when they cannot see or know what is behind the vehicle. In addition, drivers of most vehicles often find it difficult to locate and keep track of nearby vehicles or other obstacles, as when changing lanes, and these issues along with recent developments in automatic distance and braking controls have led to the introduction of front-view, side-view and rear-view cameras by vehicle manufacturers. These image sensors allow drivers to see whether obstacles are near their vehicle by using a display screen mounted, for example, on a rear view mirror or in a navigation system screen. Increasingly, such external view (e.g., front bumper, side-view, rear-view or back-up) cameras are being added to vehicles to enhance the driver's vision and to improve safety.
The external image sensors such as those known as backup or rear view cameras are typically mounted unobtrusively, and are incorporated into existing features such as the vehicle's rear name plate. These external cameras are exposed to the vehicle's harsh environmental surroundings and are often soiled by mud, salt spray or dirt which accumulates on the lens. Accumulating dirt and debris often distort the image available to the vehicle's drivers, thus creating confusion, dissatisfaction or a safety issue due to poor judgment by relying on an unclear picture.
The advent of low cost, reliable imaging devices using solid-state sensor technologies (e.g., CMOS pixel sensor technology), combined with an improved cost/performance ratio for video displays capable of meeting automotive specifications, and an increasing application rate of video monitor displays for automotive navigation systems and the like, has led to an increasing use of cameras or imaging sensors designed to give the driver a view of areas around the vehicle which are not in the normal direct field of view of the driver, typically referred to as “blind spots”. These areas include the region close to the front of the vehicle, typically obscured by the forward structure of the vehicle, the region along the passenger side of the vehicle, the region along the driver's side of the vehicle rearward of the driver, and the area or region immediately rearward of the vehicle which cannot be seen directly or indirectly through the vehicle's mirror system. The camera or imaging sensor may capture an image of the rearward (or sideward or other blind spot area) field of view, and the image may be displayed to the driver of the vehicle to assist the driver in changing lanes, backing up or reversing, or otherwise driving or maneuvering the vehicle.
The use of electronic cameras in vehicle imaging systems can significantly increase a diligent driver's knowledge of the space immediately surrounding the vehicle prior to and during low speed maneuvers, and thus contributes to the safe completion of such maneuvers. It is now well known to provide a camera or imaging sensor on a vehicle for providing an image of an exterior scene for the driver. Such a camera may be positioned within a protective housing, which may be closed about the camera or sensor and secured together via fasteners or screws or the like. For example, a metallic protective housing may be provided, such as a die cast housing of aluminum or zinc or the like. In particular, for camera sensors mounted on the exterior of a vehicle, protection against environmental effects, such as rain, snow, road splash and/or the like, and physical protection, such as against road debris, dirt, dust, and/or the like, is important. Thus, for example, in known exterior camera sensor mounts, a butyl seal, such as a hot dispensed butyl seal, or an O-ring or other sealing member or material, has been provided between the parts of the housing to assist in sealing the housing to prevent water or other contaminants from entering the housing and damaging the camera or sensor positioned therein. However, such housings typically do not provide a substantially water tight seal, and water droplets thus may enter the housing. Furthermore, any excessive vibration of the camera sensor, due to its placement (such as at the exterior of the vehicle), may lead to an undesirable instability of the image displayed to the driver of the vehicle. Also, such cameras or sensors are costly to manufacture and to implement on the vehicles.
Such vehicle vision systems often position a camera or imaging sensor at an exterior portion of a vehicle to capture an image of an exterior scene. The cameras, particularly the cameras for rearward vision systems, are thus typically placed or mounted in a location that tends to get a high dirt buildup on the camera and/or lens of the camera, with no easy way of cleaning the camera and/or its lens. In order to reduce the dirt or moisture buildup on the lenses of such cameras, prior art developers proposed using hydrophilic or hydrophobic coatings on the lenses. However, the use of such a coating is not typically effective due to the lack of air flow across the lens, especially within a sealed housing. It has also been proposed to use heating devices or elements to reduce moisture on the lenses, within the sealed housing. However, the use of a heated lens in such applications, while reducing condensation and misting on the lens, may promote the forming of a film on the lens due to contamination that may be present in the moisture or water. Also, the appearance of such cameras on the rearward portion of vehicles is often a problem for styling of the vehicle. See, for example, prior art U.S. Pat. No. 7,965,336 to Bingle, et al. which discloses a camera module with a plastic housing that houses an image sensor, which is operable to capture images of a scene occurring exteriorly of the vehicle. Bingle's camera housing assembly is welded together with the image sensor and associated components within enclosed the plastic housing, and includes a “breathable” ventilation portion that is at least partially permeable to water vapor to allow emission of internal water vapor substantially precluding passage of water droplets and other contaminants, and so Bingle's design seeks to minimize problems arising from fluid impacting or accumulating within the housing.
Bingle also seeks to use coated lenses to keep the objective lenses' view clear, and Bingle's housing or cover is optionally provided with an anti-wetting property via a hydrophobic coating (or stack of coatings), such as is disclosed in U.S. Pat. No. 5,724,187. Bingle notes that a hydrophobic property on the outermost surface of the cover can be achieved by a variety of means, such as by use of organic and inorganic coatings or by utilizing diamond-like carbon coatings. But Bingle and others do not propose actually taking any affirmative action to remove road debris (e.g., accumulated dirt, dust, mud, road salt or other built-up debris) apart from using such coatings or surface treatments.
Based on consumer preference and at least a perceived improved ability to extract information from the image, it is desired to present an image to the driver that is representative of the exterior scene as it would be perceived by normal human vision. It is also desirable that a vehicle's imaging devices or systems be useful in all conditions, and particularly in all weather and lighting conditions. However, it is often difficult to provide an imaging sensor which is capable of providing a clear image in poor weather, especially while driving. This is because conventional imaging systems typically have difficulty resolving scene information when the camera's objective lens is partially obstructed by accumulated debris (e.g., accumulated dirt, dust, mud, road salt or other built-up debris).
In order to have effective use of the camera-based visibility systems in all weather conditions, it is desirable to have an effective method of keeping the camera lens (or the housing surface protecting the objective lens) clean, but when driving or operating a vehicle during bad weather, drivers are especially reluctant to exit the vehicle to find and inspect the camera's lens.
U.S. Pat. No. 6,834,904 (to Vaitus et al) describes the use of a “Nozzle” “in close proximity to” a lens for a vehicle's camera or vision unit, and generally discloses the structure and method for mounting a nozzle module on a vehicle liftgate. This module includes a nozzle which receives fluid from a conduit, but, as noted in the description, cleaning of the lens may be implemented in other ways, such as hydrophobic lens coatings.
Increasingly on modern vehicles, cameras or other sensors such as infrared image sensors are incorporated to provide additional information to the driver. In some cases, both types of sensors are provided in a single location, with an infrared sensor, for example, having an exterior lens with a substantially flat surface and a camera having a shaped lens, such as a “fish-eye” lens. Many of these sensing devices can become soiled and obstructed by dirt and debris common in the driving environment, eventually causing deterioration in the efficacy of one or both sensors, possibly rendering at least one of them unusable, or providing an undesirable appearance.
It is therefore desirable to periodically wash these sensing devices to reduce or eliminate the buildup of such obstructions. However, there are restrictions which are unique to certain sensor wash applications which limit use of traditional washer nozzles. Sensors may be located on or near the vehicle centerline, in close proximity to branding badges or other cosmetically important features on the vehicle, and it is undesirable to add a visible washer nozzle in this aesthetically important area. Another restriction is that sensors may have very wide fields of view, up to or exceeding 180°, so that a traditional lens washer nozzle configuration would have to be within the sensor's field of view in order to be able to direct fluid onto the sensor surface at an angle which would provide acceptable cleaning. However, a washer nozzle located within the sensor's field of view may block a significant portion of the area the sensor would otherwise be capable of monitoring. A third restriction which affects sensor wash applications is that the sensor may frequently be located on an area of the vehicle which sees higher levels of contamination than do typical washer nozzle mounting locations, such as on the front grill or the rear lift gate. Washer nozzles in these locations may be at a higher risk of being clogged by the same material which is obscuring the sensor.
In addition, when multiple image sensors are located together, the problems are multiplied, more nozzles are needed to produce more sprays, increasing the likelihood of clogging, and increasing the risks that a nozzle assembly will obstruct the field of view of one or more image sensors. There is a need, therefore, for a convenient, effective and unobtrusive system and method for cleaning exterior objective lenses and image sensors' exterior surfaces, particularly when two or more image sensors are located in close proximity to one another.